High prevalence of left ventricular systolic and diastolic asynchrony in patients with congestive heart failure and normal QRS duration

Effect of medical therapy on left ventricular ejection fraction in patients with systolic heart failure and narrow QRS duration with and without ischemic heart disease and left ventricular mechanical dyssynchrony

We studied 99 consecutive patients with class III-IV systolic heart failure with a left ventricular ejection fraction (LVEF) < or =35% and a QRS duration <120 milliseconds. Patients with cardiac resynchronization therapy were excluded. Echocardiography was performed in all patients before and after optimal standard heart failure therapy. The septal-to-posterior wall motion delay (SPWMD) > or =130 milliseconds on echocardiogram was defined as left ventricular mechanical dyssynchrony (LVMD). Sixty-nine of 99 patients (70%) had ischemic heart disease. During follow-up of 15.2 +/- 9.8 months, LVEF improvement > or =15% was greater patients in nonischemic group (50%, 15/30) than in ischemic group (9%, 6/69; P < 0.001). After adjustment for age, gender, and clinical and echocardiographic characteristics, ischemic heart disease and grade of coronary disease were persistently related to LVEF improvement > or =15% (P = 0.03 and 0.02, respectively). Twenty of 99 patients (20%) had SPWMD > or =130 milliseconds (LVMD group), and 79 of 99 patients (80%) had SPWMD <130 milliseconds (non-LVMD group). LVEF increased in both groups (P = 0.005) during follow-up, but the percentage of patients with LVEF improvement > or =15% in LVMD was greater compared with patients without LVMD (40% versus 16%, respectively, P = 0.03). In conclusion, the improvement of LVEF in patients with systolic heart failure and narrow QRS was greater in patients with nonischemic heart disease and LVMD compared with patients with ischemic heart disease and absence of LVMD during medical therapy without cardiac resynchronization therapy.

Radial dyssynchrony assessed by cardiovascular magnetic resonance in relation to left ventricular function, myocardial scarring and QRS duration in patients with heart failure

BACKGROUND

Intuitively, cardiac dyssynchrony is the inevitable result of myocardial injury. We hypothesized that radial dyssynchrony reflects left ventricular remodeling, myocardial scarring, QRS duration and impaired LV function and that, accordingly, it is detectable in all patients with heart failure.

METHODS

225 patients with heart failure, grouped according to QRS duration of <120 ms (A, n = 75), between 120-149 ms (B, n = 75) or >or=150 ms (C, n = 75), and 50 healthy controls underwent assessment of radial dyssynchrony using the cardiovascular magnetic resonance tissue synchronization index (CMR-TSI = SD of time to peak inward endocardial motion in up to 60 myocardial segments).

RESULTS

Compared to 50 healthy controls (21.8 +/- 6.3 ms [mean +/- SD]), CMR-TSI was higher in A (74.8 +/- 34.6 ms), B (92.4 +/- 39.5 ms) and C (104.6 +/- 45.6 ms) (all p < 0.0001). Adopting a cut-off CMR-TSI of 34.4 ms (21.8 plus 2xSD for controls) for the definition of dyssynchrony, it was present in 91% in A, 95% in B and 99% in C. Amongst patients in NYHA class III or IV, with a LVEF<35% and a QRS>120 ms, 99% had dyssynchrony. Amongst those with a QRS<120 ms, 91% had dyssynchrony. Across the study sample, CMR-TSI was related positively to left ventricular volumes (p < 0.0001) and inversely to LVEF (CMR-TSI = 178.3 e (-0.033 LVEF) ms, p < 0.0001).

CONCLUSION

Radial dyssynchrony is almost universal in patients with heart failure. This vies against the notion that a lack of response to CRT is related to a lack of dyssynchrony.

Optimization of the interventricular delay in cardiac resynchronization therapy using the QRS width

Optimization of the interventricular pacing delay (VV) in cardiac resynchronization therapy is time-consuming and not routinely performed. The aim of the present study was to compare the acute hemodynamic response obtained by different VV programming methods. Several methods for optimizing the VV using electrocardiographic or echocardiographic measurements were performed. The effect of programming an empirical prefixed VV of 0 ms was also evaluated. Invasive first derivative of left ventricular (LV) pressure over time (dP/dt max) was measured at several VV values, and the hemodynamic response that could be obtained by each noninvasive VV selection method was extrapolated from the curve of LV dP/dt max versus VV. The study included 25 patients (80% men, age 66 +/- 9 years, 44% ischemic). The maximum achievable LV dP/dt during biventricular pacing was obtained by a median left ventricular preactivation of 30 ms and increased the baseline unpaced LV dP/dt from 774 +/- 181 to 934 +/- 179 mm Hg/s (p <0.001). The noninvasive optimization method selected the VV leading to the narrowest QRS measured from the earliest deflection and obtained the smallest difference with regard to the maximum achievable LV dP/dt. Furthermore, of all the VV optimization methods tested, this was the only 1 that significantly improved on the hemodynamic response obtained by programming a predefined VV of 0 ms in all patients (925 +/- 178 vs 906 +/- 183 mm Hg/s; p = 0.003). In conclusion, achieving the narrowest QRS measured from the earliest deflection obtained a better acute hemodynamic response than the other VV optimization methods. It also improved the response obtained by default simultaneous biventricular pacing, although this improvement was limited in magnitude.

Echocardiographic evaluation of systolic heart failure

Echocardiography is the most commonly used modality for evaluating left ventricular size and function in the context of systolic heart failure. Traditional techniques, though extensively used, have their limitations and more recently several newer technologies have emerged that are more reproducible, provide prognostic information, guide therapies and have an important role in monitoring progress. This review will evaluate the traditional and more novel techniques used and briefly provide an overview of the role of echocardiography in guiding and monitoring therapies in patients with systolic heart failure.

Left ventricular diastolic mechanical dyssynchrony and associated clinical outcomes in children with dilated cardiomyopathy

BACKGROUND

We investigated diastolic mechanical dyssynchrony and its relation to clinical status in pediatric dilated cardiomyopathy (DCM).

METHODS AND RESULTS

We calculated a diastolic and systolic dyssynchrony index (standard deviation of time to peak tissue early diastolic/systolic velocity in 12 left ventricular segments) in 33 children with DCM and 46 control subjects. A threshold to diagnose diastolic dyssynchrony was determined, and cardiac function and clinical outcomes were compared between DCM patients with and without diastolic dyssynchrony. Left ventricular wall motion was more synchronized in diastole than in systole. The diastolic dyssynchrony index was significantly higher in children with DCM than in control subjects (28.1+/-18.1 versus 9.1+/-3.8 ms, P<0.0001). A 17-ms threshold indicated the presence of diastolic dyssynchrony. Patients who died or underwent transplantation had greater diastolic dyssynchrony (diastolic dyssynchrony index 37.9+/-20.5 versus 22.1+/-13.8 ms, P=0.01), and the rate of transplant-free survival appeared to be worse for DCM patients with diastolic dyssynchrony than for patients with synchronous DCM (hazard ratio 2.98, P=0.11; hazard ratio adjusted for disease duration 2.95, P=0.17).

CONCLUSIONS

Left ventricular diastolic mechanical dyssynchrony is common in pediatric DCM, especially in patients who subsequently experience transplantation or death, and may be associated with a decreased length of transplantation-free survival.

The utility of fragmented QRS complexes to predict significant intraventricular dyssynchrony in nonischemic dilated cardiomyopathy patients with a narrow QRS interval

BACKGROUND

Fragmented QRS complexes in the electrocardiograms (ECGs) of patients with coronary artery disease are associated with adverse cardiac events. However, there are limited data on its predictive usefulness in patients with nonischemic dilated cardiomyopathy. Left ventricular dyssynchrony is common in heart failure patients who have wide QRS intervals, but its frequency in patients with narrow QRS intervals is uncertain.

OBJECTIVES

To investigate the relationship between fragmented QRS complexes and intraventricular dyssynchrony in patients with nonischemic dilated cardiomyopathy in sinus rhythm.

METHODS

Sixty nonischemic dilated cardiomyopathy patients with sinus rhythm and narrow QRS intervals were recruited. Forty patients had a fragmented QRS in their basal ECG, and 20 patients did not have a fragmented QRS. Patients were analyzed for correlation between fragmented QRS complexes and intraventricular dyssynchrony.

RESULTS

The maximal difference in time to the peak myocardial systolic velocity between any two left ventricular segments (Max-ASE Sys), and maximal difference between Max-ASE Sys and the mean value of all segments (Max-ASE to Mean Sys) were significantly higher in patients with fragmented QRS complexes (P=0.001 and P=0.003, respectively). Seventy-two per cent of the patients with fragmented QRS complexes had significant left ventricular dyssynchrony; 15% of patients without fragmented QRS complexes had significant left ventricular dyssynchrony (P<0.0001). The presence of fragmented QRS complexes in leads corresponding to the specific ventricular segment in basal ECG was found to detect intraventricular dyssynchrony with 90.6% sensitivity (negative predictive value of 85%).

CONCLUSION

Fragmentation in the resting ECG is associated with significant intraventricular dyssynchrony in patients with nonischemic cardiomyopathy, narrow QRS and sinus rhythm. Fragmentation in ECG might be useful in identifying patients who could benefit from cardiac resynchronization therapy.

Health-e-Child project: mechanical dyssynchrony in children with dilated cardiomyopathy

OBJECTIVE

Left ventricular mechanical dyssynchrony has been poorly studied in the pediatric population with dilated cardiomyopathy. We investigated the degree of dyssynchrony in children with dilated cardiomyopathy using tissue Doppler imaging and speckle tracking strain.

METHODS

Twenty-five children with dilated cardiomyopathy were compared with healthy subjects. Left ventricular mechanical dyssynchrony was assessed by speckle tracking strain and tissue Doppler imaging. Both radial and longitudinal dyssynchrony were analyzed. Left ventricular end-diastolic diameter was measured to assess the relation between dyssynchrony and ventricular function and remodeling.

RESULTS

Radial and longitudinal dyssynchrony parameters were significantly higher in the dilated cardiomyopathy group and correlated with Z-score left ventricular end-diastolic diameter. A logarithmic correlation between left ventricular ejection fraction and left ventricular end-diastolic diameter parameters was found.

CONCLUSION

In children with dilated cardiomyopathy, tissue Doppler imaging and speckle tracking strain allowed the detection of dyssynchrony, which correlates with the severity of left ventricular function.

Incremental prognostic value of combining left ventricular lead position and systolic dyssynchrony in predicting long-term survival after cardiac resynchronization therapy

The efficacy of CRT (cardiac resynchronization therapy) can be affected by a number of factors; however, the prognostic significance of the LV (left ventricular) lead position has not been explored. The aim of the present study was to examine whether a PL (posterolateral) lead position has an additional value to systolic dyssynchrony in predicting a better survival after CRT. Patients (n=134) who received CRT were followed-up for 39±24 months. The LV lead position was determined by cine fluoroscopy, and baseline dyssynchrony was assessed by TDI (tissue Doppler imaging). The relationship between the LV lead position/dyssynchrony and mortality was compared using Kaplan–Meier curves, followed by Cox regression analysis. The all-cause and cardiovascular mortalities were 38 and 31% respectively. The presence of dyssynchrony and a PL lead position predicted a lower all-cause mortality (29 compared with 47%; log-rank χ2=5.38, P=0.02) and cardiovascular mortality (21 compared with 41%; log-rank χ2=6.75, P=0.009) than when absent. The all-cause mortality was as high as 62% when patients had neither dyssynchrony nor a PL lead position, but was reduced to 29% when both criteria were present, and was between 45 and 46% when only one criterion was present (χ2=6.79, P=0.01). The corresponding values for cardiovascular mortality were 62% when patients had neither dyssynchrony nor a PL lead position, 36–38% when patients had either dyssynchrony or a PL lead position, and 21% when patients had both criteria present (χ2=9.54, P=0.004). Combining dyssynchrony and a PL lead position independently predicted a lower all-cause morality {HR (hazard ratio), 0.496 [95% CI (confidence interval), 0.278–0.888]; P=0.018} and cardiovascular mortality [HR, 0.442 (95% CI, 0.232–0.844); P=0.013]. In conclusion, the placement of the LV lead at a PL position provides additional value to baseline dyssynchrony in predicting a lower all-cause and cardiovascular mortality during long-term follow-up after CRT.

Pathobiology of cardiac dyssynchrony and resynchronization

Cardiac resynchronization therapy (CRT) represents the major new advance for treatment of heart failure since the start of the new millennium. With this therapy, failing hearts with discoordinate contraction due to conduction delay are subjected to biventricular stimulation to "resynchronize" contraction and improve chamber function. Remarkably, CRT was mostly developed and tested in patients first, and the speed at which the concept was translated to an approved clinical therapy was unusually quick. To date, CRT is the only heart failure treatment that can both acutely and chronically improve the systolic pump performance of the failing human heart yet also enhance long-term survival. This situation underscores the importance of understanding how CRT works at the molecular and cellular levels, as these insights might shed light on new approaches to treating heart failure more generally. Over the past 7 years, my laboratory and others at Johns Hopkins have developed novel animal models for addressing this question, and new results are revealing intriguing insights into the mechanisms of CRT. This review, presented on the occasion of the Fourth Annual Douglas P. Zipes Lecture at the 2009 Scientific Sessions of the Heart Rhythm Society, highlights these advances and new directions in CRT research.

Optimization techniques in cardiac resynchronization therapy

Cardiac resynchronization therapy improves symptoms and cardiac function, as well as reduces mortality in patients with progressive congestive heart failure, reduced left ventricular ejection fraction and a left bundle branch block on the surface electrocardiogram. As many as 30% of patients fail to have an adequate response. The interplay between the atrioventricular delay and the contribution of a properly timed atrial contraction to ventricular filling along with a properly timed sequence of activation of the right and left ventricular is crucial to maximizing the benefits of cardiac resynchronization therapy devices.

The electrocardiogram in left ventricular hypertrophy: past and future

The electrocardiographic diagnosis of left ventricular hypertrophy (LVH) has been centered on improving the diagnostic sensitivity and specificity of the method, using criteria whose precise relationship to increased left ventricular mass are not established. Although the electrocardiogram (ECG) has been displaced to a secondary role in the prediction of left ventricular mass, ECG/LVH has been shown to be a strong predictor of morbidity and early mortality. There are strong clues that each of the parameters in ECG/LVH is related to cardiac contractility and ejection. It is suggested that research be redirected to an exploration of these relationships and predicted that this will lead to both a better understanding of this venerable tool and an improvement in its usefulness to the clinician and patient.

Correlation of mechanical dyssynchrony with QRS duration measured by signal-averaged electrocardiography

BACKGROUND

Preimplantation left ventricular dyssynchrony is considered a prerequisite for a beneficial response to cardiac resynchronization therapy (CRT). However, electrical dyssynchrony estimated by QRS duration (QRSd) on ECG has not been proven to be an optimal surrogate of mechanical dyssynchrony. We evaluated the correlation of mechanical dyssynchrony with QRSd as measured by signal-averaged electrocardiography (SAECG) in comparison with measurements based on conventional surface ECG and with onscreen measurements based on digital ECG.

METHODS

We included 49 consecutive patients with decompensated heart failure (40 men, aged 66.8 +/- 9.5 years), New York Heart Association (NYHA) class II-IV, and LVEF < or = 40%. QRSd was calculated by manual measurement of 12-lead ECG, on-screen measurement of computer-based ECG, and calculation of total ventricular activation time on SAECG.

RESULTS

Only 60.4% of the studied patients had QRS > or = 120 ms based on measurements derived by SAECG compared to 69.4% by using on-screen measurement of computer-based ECG and 73.5% based on surface ECG (P=0.041). Interventricular but not intraventricular delay was correlated with QRSd. The correlation of interventricular dyssynchrony with QRSd was stronger when measured by SAECG than by surface ECG (r=0.45, P=0.001 vs r=0.35, P < 0.01). Among patients with ischemic cardiomyopathy, no significant correlation was demonstrated between mechanical dyssynchrony and QRSd. In nonischemic patients, interventricular delay was significantly correlated with QRSd measured by surface ECG (r=0.45, P < 0.05) and SAECG (r=0.46, P < 0.05).

CONCLUSIONS

The use of SAECG results in different patient classification in wide QRS complex category as compared to surface ECG. Furthermore, QRSd measured by SAECG is correlated with interventricular but not intraventricular dyssynchrony in heart failure patients.

Comparison of eight echocardiographic methods for determining the prevalence of mechanical dyssynchrony and site of latest mechanical contraction in patients scheduled for cardiac resynchronization therapy

Prevalence of echocardiographically assessed mechanical dyssynchrony and consistency in detection of the latest mechanical left ventricular (LV) contracting region when different echocardiographic methods are used in the same patient remains ill-defined. The objectives of this study were to evaluate (1) the prevalence of intraventricular mechanical dyssynchrony and (2) consistency of latest mechanical LV contraction using a multiparametric approach derived from tissue Doppler imaging (TDI), 3-dimensional (3D) echocardiography, and speckle tracking in patients scheduled for cardiac resynchronization therapy (CRT). In 63 patients with heart failure scheduled for CRT, 2D echocardiography, TDI, 3D echocardiography, and speckle tracking were prospectively collected and analyzed. Prevalence of dyssynchrony was low for some tissue-velocity derived indexes (11%, 13%, and 43%) but was >or=80% for strain derived by TDI, for systolic dyssynchrony index by 3D echocardiography, and for longitudinal and radial strains by speckle tracking. Prevalence of dyssynchrony was 69% for maximum delay between anteroseptal and posterolateral walls by radial strain. Agreement among dyssynchrony indexes was generally low (kappa -0.02). Agreement of each of these echocardiographic indexes in determining, in the same patient with heart failure, the latest LV mechanical contraction site was also low (no site agreement in 77%). In conclusion, in a typical CRT population there is considerable variability among various techniques that assess prevalence of mechanical dyssynchrony and in identification of the latest mechanical LV contracting region.

Echocardiography for cardiac resynchronization therapy selection: fatally flawed or misjudged?

After the publication of the PROSPECT (Predictors of Response to CRT) trial, the use of echocardiography for the assessment of mechanical dyssynchrony and as a possible aid for selecting patients for cardiac resynchronization therapy has been heavily criticized. Calls have been made to observe the current guidelines and implant according to the entry criteria of recent major trials. However, although this approach is currently to be recommended, the attempt to identify patients who will not receive the benefits of cardiac resynchronization therapy and whose clinical condition may be worsened should continue. Devices are not analogous to drugs: initial costs are higher, complications are significant, and the device cannot readily be withdrawn. Professional resources and the costs to society are high and wasted if devices are implanted inappropriately. Rather that discarding the attempt to identify the most suitable patients pre-operatively, further work is needed to refine the techniques and new clinical trials performed. A combination of methods that include finding the site of latest mechanical activation, myocardial scar localization, and assessing venous anatomy pre-operatively may help to identify those who will not derive any benefit or be potentially worsened.

Variability in tissue Doppler echocardiographic measures of dyssynchrony is reduced with use of a larger region of interest

BACKGROUND

Doppler tissue imaging (DTI)-based dyssynchrony parameters failed to predict response to cardiac resynchronization therapy (CRT) in the multicenter Predictors of Response to Cardiac Resynchronization Therapy (PROSPECT) trial. Large variability during the interpretation of DTI data was one of several factors thought to contribute to this failure. In this study, the authors hypothesized that using larger regions of interest (ROIs) to generate velocity curves from Doppler tissue images would significantly reduce the variability of DTI dyssynchrony parameters.

METHODS

The variability of 3 ROI sizes (6 x 6, 18 x 6, and 30 x 6 mm) was compared in 30 patients undergoing CRT. Variability due to manual ROI placement was determined for each ROI size by placing 3 ROIs in each myocardial segment, 6mm apart from one another. Thus, 3 velocity curves were generated for each segment and each ROI size. Four published dyssynchrony parameters were calculated from all permutations of the 3 ROI positions per segment. A mean modified coefficient of variation was calculated for each parameter and ROI size.

RESULTS

The 6 x 6 mm ROI had a mean coefficient of variation of 27%. The 18 x 6 and 30 x 6 mm ROIs had significantly lower coefficients of variation (17% and 14%, respectively) than the 6 x 6 mm ROI (P < .01 for both). The 30 x 6 mm ROI also reduced the diagnostic inconsistency of dyssynchrony parameters by 44% (P = .024) compared with the 6 x 6 mm ROI.

CONCLUSION

Using a 30 x 6 mm ROI instead of a 6 x 6 mm ROI to quantify tissue Doppler dyssynchrony reduces variability by 47% and diagnostic inconsistency by 44%. The authors recommend using a 30 x 6 mm ROI in future trials to minimize variability.

Left ventricular systolic and diastolic dyssynchrony in coronary artery disease with preserved ejection fraction

The present study aims to evaluate LV (left ventricular) mechanical dyssynchrony in CAD (coronary artery disease) with preserved and depressed EF (ejection fraction). Echocardiography with TDI (tissue Doppler imaging) was performed in 311 consecutive CAD patients (94 had preserved EF > or =50% and 217 had depressed EF <50%) and 117 healthy subjects to determine LV systolic and diastolic dyssynchrony by measuring Ts-SD (S.D. of time to peak myocardial systolic velocity during the ejection period) and Te-SD (S.D. of time to peak myocardial early diastolic velocity during the filling period) respectively, using a six-basal/six-mid-segmental model. In CAD patients with preserved EF, both Ts-SD (32.2+/-17.3 compared with 17.7+/-8.6 ms; P<0.05) and Te-SD (26.2+/-13.6 compared with 20.3+/-8.1 ms; P<0.05) were significantly prolonged when compared with controls, although they were less prolonged than CAD patients with depressed EF (Ts-SD, 37.8+/-16.5 ms; and Te-SD, 36.0+/-23.9 ms; both P<0.005). Patients with preserved EF who had no prior MI (myocardial infarction) had Ts-SD (32.9+/-17.5 ms) and Te-SD (28.6+/-14.8 ms) prolonged to a similar extent (P=not significant) to those with prior MI (Ts-SD, 28.4+/-16.8 ms; and Te-SD, 25.5+/-15.0 ms). Patients with class III/IV angina or multi-vessel disease were associated with more severe mechanical dyssynchrony (P<0.05). Furthermore, the majority of patients with mechanical dyssynchrony had narrow QRS complexes in those with preserved EF. This is in contrast with patients with depressed EF in whom systolic and diastolic dyssynchrony were more commonly associated with wide QRS complexes. In conclusion, LV mechanical dyssynchrony is evident in CAD patients with preserved EF, although it was less prevalent than those with depressed EF. In addition, mechanical dyssynchrony occurred in CAD patients without prior MI and narrow QRS complexes.

Prediction of short-term outcomes in patients with idiopathic dilated cardiomyopathy referred for transplantation using standard echocardiography and strain imaging

OBJECTIVE

We sought to evaluate the short-term prognostic value of echocardiography including two-dimensional (2D) strain imaging in patients with end-stage idiopathic dilated cardiomyopathy (IDCM).

METHODS

To evaluate the short-term (6-month) prognostic value of different parameters used for the assessment of IDCM patients referred for heart transplantation, we performed at the baseline transthoracic echocardiography including 2D strain imaging, N-terminal pro-BNP measurements, and exercise testing for all patients included in the study. After 6 months, all parameters, including endsystolic strain (ESS), peak systolic strain rate (SSR(max)), early and late diastolic strain rates, their ratio (diastolic strain rate E [DSR(E)], dialostolic strain rate A [DSR(A)], diastolic strain rate E and A wave ratio [DSR(E/A)]), and systolic intraventricular dyssynchrony indexes (IVDSI) were tested for their prognostic value to predict a patient's outcome.

RESULTS

At the baseline stable patients had significantly lower transmitral E and A wave ratio (E/A), DSR(E/A), higher DSR(A) values, longer transmitral E wave deceleration time (DcT), higher longitudinal ESS and SSR(max) values, lower systolic circumferential and longitudinal IVDSI.

CONCLUSION

The highest sensitivity for rapid heart failure progression was shown by DcT <100 ms, E/A > 1.5, DSR(A) < 0.3/s, circumferential IVDSI > 0.16, and longitudinal IVDSI > 0.22 (91%, 78%, 94%, 83%, and 75%, respectively).

Long-term impact of right ventricular septal versus apical pacing on left ventricular synchrony and function in patients with second- or third-degree heart block

Right ventricular (RV) septal pacing has been advocated as an alternative to apical pacing to avoid long-term detrimental effects. There is conflicting evidence on the benefits of RV septal pacing. Fifty-five subjects (22 normal healthy controls, 17 with RV septal pacing, and 17 with apical pacing) were recruited. Midventricular short-axis left ventricular (LV) circumferential and radial strains were determined. Circumferential and radial strain dyssynchrony and longitudinal systolic dyssynchrony were determined. Echocardiographic determination of pacing sites were compared with electrocardiogram and chest x-ray. Septal pacing is a heterogenous group of different pacing sites, and there was only modest agreement among echocardiogram, electrocardiogram, and chest x-ray. Median pacing durations were 436 days for septal pacing and 2,398 days for apical pacing. Mean QRS duration for apical pacing was longest, followed by septal pacing and control (p <0.001). LV mass index, end-systolic volume index, and ejection fraction were more impaired in septal than in apical pacing (all p values <0.05). Septal pacing was associated with more impaired circumferential strain (p <0.001) and worse LV dyssynchrony than apical pacing and control. In conclusion, standard fluoroscopic and electrocardiographic implantation techniques for RV septal pacing resulted in a heterogenous group of different pacing sites. This heterogenous RV septal pacing group was associated with poorer long-term LV function and greater dyssynchrony than RV apical pacing and control.

Utility of QRS width and echocardiography parameters in an integrative algorithm for selecting heart failure patients with cardiac dyssynchrony

BACKGROUND

Cardiac resynchronization therapy (CRT) is an effective treatment in dilated cardiomyopathy (DCM). However, it has been demonstrated that mechanical dyssynchrony is not related to electrical dyssynchrony. We hypothesized that a new QRS width cutoff could be easier to use as a first step in the selection of patients with inter- and intraventricular dyssynchrony.

METHODS

We included 58 patients with DCM. Electrocardiographic (PR interval and QRS width) and echocardiographic (left ventricular dimensions, systolic and diastolic function, dyssynchrony parameters) data were evaluated in all patients.

RESULTS

According to QRS width, we divided the study population in two groups: Group 1, 25 patients having a narrow QRS (<or=120 ms), and Group 2, 33 patients having a wide QRS (>120 ms). Patients in Group 2 had larger left ventricles, with similar systolic function and more severe diastolic dysfunction than patients with narrow QRS. Interventricular dyssynchrony was more frequent in group 2 (54.5% vs 20%, p=0.01), while intraventricular dyssynchrony was highly prevalent in both groups (82.1% vs 72%, p=0.48). A QRS>140 ms best predicted the presence of interventricular dyssynchrony (sensitivity 78.2% and specificity 63.6%), while a QRS>150 ms best predicts intraventricular dyssynchrony (sensitivity 48.6% and specificity 80%).

CONCLUSIONS

Intraventricular dyssynchrony has a high prevalence in patients with DCM, irrespective of the QRS width. Using a higher QRS width cutoff (150 ms) might help in patient selection for CRT. Electrocardiography and echocardiography can be combined into a selection algorithm for patients receiving resynchronization therapy.

Imaging in cardiac resynchronization therapy: what does the clinician need?

In the guidelines, criteria to select patients for cardiac resynchronization therapy (CRT) are based only on the QRS duration on surface electrocardiogram (ECG) as a marker of cardiac dyssynchrony. From a theoretical point, imaging techniques would be useful to improve patient's selection with an analysis of the atrio-ventricular, interventricular and intraventricular dyssynchrony. Imaging techniques may also identify physiopathological issues such as the presence of scar, right ventricular dysfunction, or severe pulmonary hypertension. New echocardiographic techniques appear promising, but the role of echocardiography in the identification of mechanical dyssynchrony remains to be clearly defined in prospective multicentre trials. The positioning of left ventricular lead could be optimized using different imaging techniques to assess the site of latest activation and the coronary sinus anatomy. Finally, imaging techniques may have an important role to optimize the programming of the device, especially the different cardiac timings. In the present article, we focused on echocardiography, multislices-computed tomography, and magnetic resonance imaging being discussed elsewhere.

Left ventricular dyssynchrony in hypertensive patients without congestive heart failure

BACKGROUND

Normal left ventricular (LV) systolic function is present in as many as 50% of patients with congestive heart failure. The majority of such patients have systemic hypertension. Recent studies have demonstrated LV dyssynchrony among patients with heart failure and normal systolic function. However, it is unclear whether such abnormalities exist in hypertensive patients who have not developed clinical evidence of heart failure.

METHODS

Hospitalized patients with established hypertension undergoing echocardiography who met the following criteria were eligible for the study: LV ejection fraction (EF) >or= 50%, wall >or=11 mm, absence of valvular or known ischemic disease, and normal QRS duration. Complete 2-Dimensional and Doppler echocardiography studies with tissue Doppler imaging (TDI) were performed in all patients. Dyssynchrony was measured using time from QRS to peak systolic velocity on TDI (T-P) in 3 apical views. Normal values for dyssynchrony were established in a group of normotensive patients with normal echocardiography studies.

RESULTS

The study included 42 patients (19 women, 23 men with a, mean age of 59.6 y (range 32-96 y). Left ventricular dyssynchrony was common, occurring in 20 of 42 patients (47.6%). Dyssynchrony assessed with the maximum T-P (T-Pmax) was significantly related to LV mass (r = 0.32, p = 0.036), left atrial volume (r = 0.59, p < 0.0001), and LV sphericity index (0.32, p = 0.037). Dyssynchrony was not related to age or LV filling pressure calculated from the Doppler study.

CONCLUSIONS

Left ventricular dyssynchrony is common among hypertensive patients with normal LV systolic function and no evidence of congestive heart failure. The severity of LV dyssynchrony is related to the magnitude of LV hypertrophy, left atrial size, and LV remodeling.

Prevalence and inter-relationship of different Doppler measures of dyssynchrony in patients with heart failure and prolonged QRS: a report from CARE-HF

BACKGROUND

Cardiac resynchronisation therapy (CRT) improves mortality and morbidity in heart failure patients with wide QRS. Observational studies suggest that patients having more left ventricular dyssynchrony pre-implantation obtain greater benefit on ventricular function and symptoms with CRT.

AIM

To provide an analysis of the prevalence and type of dyssynchrony in patients included in the CARE-HF trial.

METHODS

100 patients 67 (58 to 71) years were examined with echocardiography including tissue doppler imaging before receiving a CRT-pacemaker. Atrio-ventricular dyssynchrony (LVFT/RR) was defined as left ventricular filling time <40% of the RR-interval. Inter-ventricular mechanical delay (IVMD) was measured as the difference in onset of Doppler-flow in the pulmonary and aortic outflow tracts >40 ms. Intra-ventricular (regional) dyssynchrony in a 16-segment model was expressed either as a delayed longitudinal contraction (DLC) during the postsystolic phase or by tissue synchronisation imaging (TSI) with a predefined time-difference in systolic maximal velocities >85 ms.

RESULTS

LVFT/RR was present in 34% and IVMD in 60% of patients while intra-ventricular dyssynchrony was present in 85% (DLC) and 86% (TSI) with a high agreement between the measures (Kappascore 0.86-1.00), indicating the methods being interchangeable. Patients with cardiomyopathy (53%) were more likely to have LVFT/RR <40% (45% vs. 21% (p= 0.02)) and more segments affected by intra-ventricular dyssynchrony 4(3, 5) vs. 3(1, 4), p = 0.002, compared to patients with ischemic heart disease.

CONCLUSION

The prevalence of intra-ventricular dyssynchrony is high in patients with heart failure, wide QRS and depressed systolic function. Most important, TSI appears to be a fast and reliable method to identify patients with intra-ventricular dyssynchrony likely to benefit from CRT.

Cardiac resynchronization therapy

Systolic heart failure is a major problem for Americans today, with 550,000 new cases diagnosed per year, and ultimately contributes to 287,000 deaths annually. While pharmacologic therapy has drastically improved outcomes in patients with systolic heart failure, hospitalizations from systolic heart failure continue to increase and remain a major cost burden. In response to this unmet need, recent years have seen dramatic improvements in device-based therapy targeting one cause of systolic dysfunction: dyssynchronous ventricular contraction. Cardiac resynchronization therapy aims to restore mechanical synchrony by electrically activating the heart in a synchronized manner. This review summarizes the rationale for cardiac resynchronization therapy, evidence for its use, current guidelines, and ongoing and future directions for research.

Echocardiographic parameters of mechanical synchrony in healthy individuals

Definition and validation of the ranges of normal values and agreement among echocardiographic measures of mechanical synchrony in healthy subjects are mostly lacking. The aims of this study were (1) to assess the ranges of normal values for 5 tissue Doppler imaging parameters, real-time 3-dimensional echocardiographic measures, and speckle-tracking measures of mechanical synchrony; (2) to evaluate interinstitutional variability; (3) to compare the ranges of normal values with those reported in previous research; and (4) to analyze the agreement among all parameters in the same healthy subject. Time to peak systolic velocity (Ts), the delay between Ts at the basal septal and lateral segments, peak velocity difference, strain derived by tissue Doppler imaging, Ts derived by tissue synchronization imaging, systolic synchrony index (SSI) derived by real-time 3-dimensional echocardiography, and longitudinal and radial strain derived by speckle tracking were prospectively collected and analyzed at 2 different institutions in 160 consecutive healthy subjects. The ranges of normal values, expressed as means +/- 2 SDs, were 30.32 +/- 29.36 ms for the SD of Ts, 15.51 +/- 99.88 ms for septal-lateral delay, 60.75 +/- 81.62 ms for peak velocity difference, 33.07 +/- 29.96 ms for tissue synchronization imaging, 34.16 +/- 23.26 ms for the SD of strain, 2.74 +/- 2.16% for SSI, 28.91 +/- 23.02 ms for the SD of longitudinal strain, and 10.4 +/- 6.31 ms for radial strain. There was large interinstitutional variability for all parameters. Three-dimensional SSI and radial strain were within the published upper range limit for healthy subjects. Ninety percent of healthy subjects were consistently classified to be synchronous by 1 parameter. With a composite index, more subjects than expected showed dyssynchrony (10% vs 2.5%). In conclusion, 3-dimensional SSI and radial strain were the most reproducible parameters and consistently discriminated normal healthy subjects from the cardiac resynchronization therapy volume responders.